Filling adapter and injection solution transferring system

ABSTRACT

A filling adapter (12) for connecting a syringe (14) containing an injection solution to an injection device (10), the filling adapter (12) comprises a hollow sleeve (16) and an adapter element (18) accommodated within the sleeve (16), wherein the adapter element (18) comprises a first connecting port (20) adapted to be connected to the syringe (14) and a second connecting port (22) adapted to be connected to the injection device (10), and wherein the adapter element (18) is provided with a through-opening (26) extending therethrough. A cannula (27) protrudes from the second connecting port (22) of the adapter element (18), wherein the cannula (27) is arranged in fluid communication with the through-opening (26) extending through the adapter element (18), and wherein the adapter element (18) further is provided with a venting device (64) which is adapted to vent gas introduced from the syringe (14) into the injection device (10) via the through-opening (26) and the cannula (27) into the ambient.

The invention relates to a filling adapter for connecting a syringe to an injection device, in particular a micro dose injection device such as, for example, an ophthalmic injection device for intraocular use. Further, the invention relates to an injection solution transferring system for transferring an injection solution from a syringe to an injection device, in particular a micro dose injection device such as, for example, an ophthalmic injection device for intraocular use.

Typically, an injection solution to be administered to a patient for medical treatment is stored within a syringe having a container for accommodating the injection solution and a plunger which is displaceable relative to the container in order to expel the injection solution from the container. In case the medical treatment plan for a patient provides for the administration of a dose of the injection solution which corresponds to the filling volume of the syringe or in case the dosage of the injection solution is of minor importance for the desired therapeutic effect, the injection solution may be administered to the patient directly from the syringe. However, in case the medical treatment plan for a patient requires the administration of a dose of the injection solution which differs from the filling volume of the syringe and/or in case an accurate dosage of the injection solution is necessary, the injection solution, prior to administration, may be transferred from the syringe to an injection device which finally is used to inject the desired dose of the injection solution into the patient.

US 2011/0214777 A1 describes a method and a device for the sterile filling of a disposable injector with a defined dose of an injection solution which initially is stored in the interior of a container of a needle syringe. The device according to US 2011/0214777 A1 comprises a double-cone adapter provided with a through-bore which, at a first end, adheres to a closure cap of the disposable injector via an external cone with a force fit and/or a form fit so as to close a recess of a barrel of the injector in a sterile, gas-tight and liquid-tight manner. At a second end, the adapter is provided with a recess which receives a head of the needle syringe in a gas-tight and liquid-tight manner, while the through-bore engages around the needle with minimal play. As a result, the needle syringe is fixed in the adapter in a gas-tight and liquid-tight manner or is locked therein. Thereafter, all of the injection solution stored in the needle syringe is forced or sucked into the barrel of the injector by pressing in a needle syringe piston by means of a piston rod or by pulling back a piston of the injector by means of a pump rod. After detaching the needle syringe and the adapter from the closure cap of the injector and after removing any air from the barrel of the injector, the injector may be activated for being placed on an injection site by tearing off a tear-off banderole and by removing the closure cap.

The invention is directed at the object of providing a filling adapter for connecting a syringe containing an injection solution to an injection device, in particular a micro dose injection device, which allows the accurate and reliable preparation of a micro dose of the injection solution within the injection device. Further, the invention is directed at the object of providing an injection solution transferring system for transferring an injection solution from a syringe to an injection device, in particular a micro dose injection device, which allows the accurate and reliable preparation of a micro dose of the injection solution within the injection device.

This object is addressed by a filling adapter as defined in claim 1 and an injection solution transferring system as defined in claim 10.

A filling adapter for connecting a syringe containing an injection solution to an injection device comprises a hollow sleeve. The hollow sleeve preferably is provided with an inner lumen which is dimensioned so as to allow the insertion of at least a distal portion of the syringe at one end and of at least a distal portion of the injection device at an opposing end of the hollow sleeve. The cross-sectional shape of the hollow sleeve and in particular of the inner lumen of the hollow sleeve may be adapted to the outer contour of the syringe and the injection device to be connected with the aid of the filling adapter. For example, the hollow sleeve may have a substantially circular hollow cylindrical shape and the lumen extending therethrough may have a substantially circular cross-sectional shape.

An adapter element is accommodated within the sleeve. The adapter element comprises a first connecting port adapted to be connected to the syringe, in particular a distal end of the syringe. The adapter element also comprises a second connecting port adapted to be connected to the injection device, in particular a distal end of the injection device. Preferably, the first and the second connecting port are provided in the region of opposing ends of the adapter element in a direction along a longitudinal axis of the filling adapter. Furthermore, the adapter element is provided with a through-opening extending therethrough. Preferably, the through-opening extends substantially parallel to the longitudinal axis of the filling adapter.

The adapter element is capable of establishing a fluid connection between the syringe and the injection device, i.e. when the syringe is connected to the first connecting port of the adapter element and the injection device is connected to the second connecting port of the adapter element, the injection solution contained in the syringe may be transferred into the injection device, for example by manually pushing a plunger of the syringe so as to expel the injection solution from the distal end of the syringe into the through-opening provided in the adapter element and further into a receptacle of the injection device.

The filling adapter further comprises a cannula which protrudes from the second connecting port of the adapter element and which is arranged in fluid communication with the through-opening extending through the adapter element. The cannula may be designed in the form of a stainless steel tube. Further, the cannula may be attached to the adapter element. The cannula and the adapter element may be designed so as to generate a close slide fit between the cannula and a cannula receiving bore provided in the adapter element in order to prevent the generation of wear particles from the adapter element upon attaching the cannula. In addition, the cannula may be provided with bevelled ends in order to further minimize wear particle generation upon attaching the cannula to the adapter element. A final bonding between the cannula and the adapter element may be effected by means of a UV-cured glue.

When the injection device is connected to the second connecting port of the adapter element, the cannula extends into the receptacle of the injection device, i.e. a distal tip of the cannula is arranged at a distance from the distal end of injection device within the interior of the receptacle of the injection device. As a result, the injection solution exiting the syringe, via the cannula, is supplied to the receptacle of the injection device not in the region of the distal end of the injection device, but at a position arranged at a distance from the distal end of the injection device within the interior of the receptacle.

By simply holding the filling adapter and the injection device in an upright position with longitudinal axes of the filling adapter and the injection device being oriented substantially vertically and with the distal end of the injection device facing downwards, a gravity-driven flow of the injection solution from the distal tip of the cannula downwards in a direction of the distal end of the injection device and further in the direction of the adapter element can be induced. Gas bubbles which are entrapped within the injection solution and hence transferred from the syringe to the injection device together with the liquid phase of the injection solution are entrained with this gravity-driven flow and, due to the higher specific density of the liquid phase of the injection solution, are forced in the direction of the distal end of the injection device and further in the direction of the adapter element.

Finally, the adapter element is provided with a venting device which is adapted to vent gas introduced from the syringe into the injection device via the through-opening and the cannula into the ambient. The venting device thus allows entrapped gas bubbles, in particular air bubbles, that are conveyed from the distal tip of the cannula back to the adapter element by the above described gravity-driven flow of the injection solution to be expelled into the ambient. In order to ensure that gas bubbles entrapped in the injection solution can be vented to the ambient as desired without expelling a substantial amount of the liquid phase of the injection solution to the ambient, the design, in particular the shape and the dimensions of the venting device may be adjusted in dependence on the physical properties, in particular the specific density, the viscosity and the surface tension of the injection solution.

The filling adapter allows a gas free filling of the injection device with the injection solution. As a result, manually expelling entrapped gas from the syringe prior to connecting the syringe to the filling adapter can be dispensed with thus simplifying the procedure which has to be carried out by a user for transferring the injection solution from the syringe to the injection device. Furthermore, an accurate and reliable preparation of a desired dose of the injection solution within the injection device is made possible. Consequently, the filling adapter is particularly suitable for use upon transferring an injection solution from a syringe to a micro dose injection device, for example an ophthalmic injection device for intraocular use.

The first connecting port of the adapter element may form female Luer taper which is adapted to interact with a male Luer taper provided at the distal end of the syringe. As a result, the distal end of the syringe can easily and quickly be connected to the adapter element in a fluid-tight manner.

The through-opening extending through the adapter element may comprise an inlet section which is arranged adjacent to the first connecting port. In use of the filling adapter, injection solution expelled from the syringe thus may enter the through-opening via its inlet section. The inlet section of the through-opening preferably has a flow cross-section which decreases in a direction of flow of the injection solution expelled from the syringe during use of the filling adapter.

Further, the through-opening may comprise an intermediate section which, in the direction of flow of the injection solution expelled from the syringe during use of the filling adapter, is arranged downstream of the inlet section. The intermediate section of the through-opening preferably has a substantially constant flow cross-section. In particular, the flow cross-section of the intermediate section substantially corresponds to the smallest flow cross-section of the inlet section adjacent to the intermediate section.

Finally, the through-opening may comprise a receiving section which, in the direction of flow of the injection solution expelled from the syringe during use of the filling adapter, is arranged downstream of the intermediate section, i.e. adjacent to the second connecting port. The receiving section serves to receive a part of the injection solution which is expelled from the distal tip of the cannula and which in a gravity-driven manner flows back in the direction of the adapter element. Preferably, the receiving section has a flow cross-section that is larger than the flow cross-section of the intermediate section.

In a preferred embodiment of the filling adapter, the cannula extends into at least a portion of the intermediate section of the through-opening. In other words, the intermediate section of the through-opening or a portion thereof may define a cannula receiving bore of the adapter element wherein a proximal end of the cannula may be fixed. The cannula then extends from the intermediate section of the through-opening, through the receiving section of the through-opening and the second connecting port so as to protrude from the second connecting port. Preferably, the receiving section of the through-opening, the second connecting port and the hollow sleeve define a concentric arrangement around the cannula.

The venting device preferably comprises at least one radial bore connecting the through-opening extending through the adapter element to the ambient. In particular, the at least one radial bore of the venting device connects the receiving section of the through-opening to an outer circumferential surface of the adapter element and hence to the ambient. In order to ensure that gas bubbles entrapped in the injection solution can be vented to the ambient as desired without expelling a substantial amount of the liquid phase of the injection solution to the ambient, the flow cross-section, i.e. the diameter of the radial bore may be selected in dependence on the physical properties, in particular the specific density, the viscosity and the surface tension of the injection solution. In a particularly preferred embodiment of the filling adapter, the venting device comprises two radial bores which coaxially extend from an outer circumferential surface of the adapter element to the receiving section of the through-opening so as to connect the receiving section of the through-opening to the ambient.

The filling adapter may be used to connect a syringe to an injection device comprising an inner injection solution receptacle which is contained within a protective outer barrel. The inner injection solution receptacle may be formed integral with the protective outer barrel. Further, in the region of its proximal end, the protective outer barrel may be provided with a flange element which may serve to connect the protective outer barrel and the inner injection solution receptacle to a housing of the injection device. For example, the housing of the injection device may comprise a suitably shaped and dimensioned receptacle for receiving the flange element and hence fastening the protective outer barrel and the inner injection solution receptacle to the housing.

Such an injection device is in particular suitable for administering a micro dose of an injection solution to a patient. The second connecting port of the adapter element then preferably forms a female Luer taper which is adapted to interact with a male Luer taper provided at a distal end of the injection solution receptacle of the injection device. A result, a fluid-tight connection can be established between the distal end of the injection solution receptacle of the injection device and the adapter element in a simple manner. Furthermore, the second connecting port of the adapter element, in particular in the region of its outer circumference, may be provided with a Luer thread which is adapted to interact with a complementary Luer thread provided at an outer barrel of the injection device, in particular in the region of an inner circumference of the outer barrel of the injection device. As a result, also a reliable connection between the outer barrel of the injection device and the adapter element can be effected.

In a preferred embodiment of the filling adapter, the adapter element is provided with at least one retention shoulder which protrudes from the outer circumferential surface of the adapter element and which interacts with a complementary crush rib protruding from an inner circumferential surface of the hollow sleeve in order to fix the adapter element in its position within the hollow sleeve. In particular, the retention shoulder and the complementary crush rib are adapted to create an interference fit so as to reliably fix the adapter element in its position within the hollow sleeve. By the interaction between the retention shoulder of the adapter element and the complementary crush rib of the hollow sleeve, correct positioning, i.e. in particular concentricity of the adapter element and hence the cannula within the hollow sleeve can be ensured. As a result, the cannula is prevented from contacting the injection device, in particular an injection solution receptacle of the injection device which accommodates the cannula, upon connecting the filling adapter to the injection device. Hence, the generation of wear particles is prevented.

In a preferred embodiment of the filling adapter, the retention shoulder protrudes from the outer circumferential surface of the adapter element in the region of the inlet section and/or the intermediate section of the through-opening extending through the adapter element. Such a configuration ensures that, in the region of the receiving section of the through-opening extending through the adapter element, an air gap is present between the outer circumferential surface of the adapter element and the inner circumferential surface of the hollow sleeve which allows an unhindered function of the venting device, i.e. an unhindered exit of gas from receiving section via the at least one radial bore of the venting device.

In the region of a first end which faces the syringe when the syringe is brought into engagement with the first connecting port of the adapter element, the hollow sleeve may comprise at least one resilient clip which is adapted to engage with a collar of the syringe when the syringe is brought into engagement with the first connecting port. For example, the resilient clip may comprise an arm which extends in a recess provided in the hollow sleeve substantially parallel to the longitudinal axis of the filling adapter in the direction of the first end of the hollow sleeve. A latching nose may protrude from an inner surface of the arm in the region of a free end of the arm. When the syringe is brought into engagement with the first connecting port, due to the interaction with the collar of the syringe, the resilient clip is bent outwards. When, however, the syringe has reached its final position with respect to the adapter element, i.e. when the distal tip of the syringe is connected to the first connecting port of the adapter element, the resilient clip resumes its original position substantially parallel to the longitudinal axis of the filling adapter such that the latching nose comes into engagement with an end face of the collar of the syringe. As a result, the syringe is firmly connected to the hollow sleeve. Preferably, the hollow sleeve comprises at least two resilient clips.

In the region of its first end which faces the syringe when the syringe is brought into engagement with the first connecting port of the adapter element, the hollow sleeve at its outer circumferential surface may be provided with at least one first gripping structure. For example, the first gripping structure may be designed in the form of a nub array. The first gripping structure simplifies the handling of the filling adapter, in particular during bringing the syringe into engagement with the first connecting port of the adapter element.

In the region of a second end which faces the injection device when the injection device is brought into engagement with the second connecting port of the adapter element, the hollow sleeve at its outer circumferential surface may be provided with at least one second gripping structure. For example, the second gripping structure may be designed in the form of a gripping rib array with individual gripping ribs extending substantially parallel to the longitudinal axis of the filling adapter. The second gripping structure simplifies the handling of the filling adapter, in particular during bringing the injection device into engagement with the second connecting port of the adapter element.

The hollow sleeve may further be provided with at least one longitudinal guiding rib which protrudes from the inner circumferential surface of the hollow sleeve and which is adapted to guide the injection device into engagement with the second connecting port. The guiding function of the at least one guiding rib prevents the cannula of the filling adapter from contacting the injection device, in particular an injection solution receptacle of the injection device which accommodates the cannula, upon connecting the filling adapter to the injection device. As a result, the generation of wear particles is prevented.

Preferably, the hollow sleeve and the at least one longitudinal guiding rib are designed, i.e. shaped and dimensioned, in such a manner that a close sliding fit is generated between the guiding rib and an outer surface of the injection device, in particular an outer surface of an outer barrel of the injection device. As a result, the filling adapter can be detached from the injection device after completion of the filling process in a smooth manner and without generating wear. If need be, the hollow sleeve may comprise a plurality, for example three longitudinal guiding ribs which protrude from the inner circumferential surface of the hollow sleeve and which extend substantially parallel to the longitudinal axis of the filling adapter.

In a preferred embodiment of the filling adapter, the hollow sleeve, in at least one of the region of its first end which faces the syringe when the syringe is brought into engagement with the first connecting port of the adapter element and the region of its second end which faces the injection device when the injection device is brought into engagement with the second connecting port of the adapter element, has an outer diameter which is larger than an outer diameter of the hollow sleeve in an intermediate section arranged between the first and the second end. Such a design of the hollow sleeve simplifies the gripping and thus the handling of the filling adapter.

The hollow sleeve may be provided with at least one observing window for observing the filling of the injection device with the injection solution from the syringe. In a particular preferred embodiment of the filling adapter, the hollow sleeve comprises two observing windows allowing an unhindered view of interior of the injection device. The observing window preferably is arranged in such a position that it provides an unhindered view of the distal tip of the cannula.

Preferably, the hollow sleeve extends beyond a distal tip of the cannula. As a result, a user is protected from the cannula during handling of the filling adapter.

An injection solution transferring system comprises an injection device adapted to be filled with an injection solution from a syringe. The injection device may be designed in the form of a micro dose injection device which allows the administration of a micro dose of the injection solution to a patient, specifically a paediatric patient. In particular, the injection device may be an ophthalmic injection device for intraocular use. In a particularly preferred embodiment of the injection solution transferring system, the injection device comprises an inner injection solution receptacle which is contained within a protective outer barrel. Further, the system comprises an above-described filling adapter for connecting the syringe to the injection device.

Basically, the injection solution transferring system comprises only the injection device and the filling adapter. In a preferred embodiment of the injection solution transferring system, however, also the syringe which contains an injection solution forms a part of the injection solution transferring system. The syringe may be a pre-filled syringe which may, for example, contain an injection solution for intraocular use.

In a preferred embodiment of the injection solution transferring system, the injection device further comprises a plunger which, during use of the injection device, serves to discharge injection solution received in the injection device from the injection device. The plunger may be made of polycarbonate. At least a portion of the plunger may be slidably received within the injection solution receptacle of the injection device. At its proximal end, the plunger may carry an actuation button which may be depressed by a user in order to displace the plunger relative to the injection solution receptacle in a distal direction along a longitudinal axis of the plunger. At its distal end, the plunger may be provided with a tip element which may be attached to a plunger rod. A coupling between the plunger rod and the tip element may be effected, for example, by the interaction of a tip barb provided at a distal end of the plunger rod with a barb receptacle of the tip element. Further, the tip element may be provided with a sealing element which, for example, may be provided in the region of an outer circumferential surface of the tip element and which sealingly interacts with an inner circumferential surface of the injection solution receptacle.

The plunger of the injection device may be adapted to be arranged in a filling position wherein a distal tip thereof is disposed at a desired distance from a distal tip of the cannula of the filling adapter when the injection device is engaged with the second connecting port of the adapter element of the filling adapter. When the plunger of the injection device is arranged in its filling position, its distal tip, i.e. a distal end face of the tip element provided at the distal tip of the plunger, preferably is arranged at a close distance from the distal tip of the cannula. For example, the injection device and the filling adapter may be designed so as to set the distance between the distal tip of the plunger of the injection device and the distal tip of the cannula of the filling adapter to approximately 1.5 mm+/−0.5 mm. By arranging the distal tip of the plunger of the injection device and the distal tip of the cannula of the filling adapter at a close distance, the injection solution supplied to the injection device via the cannula is reliably forced to flow in the direction of the venting device.

As a result, air-free filling of the injection device with the injection solution can be ensured.

The injection device may be delivered with the plunger being arranged in its filling position. The filling position of the plunger may be a proximal end position of the plunger, i.e. the injection device may be designed in such a manner that a movement of the plunger further in a proximal direction than into its filling position is prevented. In order to achieve this, the injection device may comprise a plunger positioning mechanism which is adapted to allow a movement of the plunger relative to the injection solution receptacle of the injection device from its filling position in a distal direction, but to prevent a movement of the plunger relative to the injection solution receptacle of the injection device from its filling position in a proximal direction. The plunger positioning mechanism may, for example, comprise a distal end face of a guiding channel which is provided in a circumferential surface of the plunger, which extends along the longitudinal axis of the plunger and which receives a guiding element which is provided, for example, on a housing of the injection device in a guiding manner. An interaction between the distal end face of the guiding channel and the guiding element then may define the proximal end position and hence the filling position of the plunger.

In a particularly preferred embodiment of the injection solution transferring system, the injection device further comprises a plunger locking mechanism which is adapted to interact with the filling adapter, in particular the hollow sleeve of the filling adapter, so as to prevent the plunger of the injection device from being moved from its filling position in a distal direction, i.e. in the direction of the distal tip of the cannula of the filling adapter, when the injection device is connected to the filling adapter. In particular, the plunger locking mechanism of the injection device may interact with a locking rim of the hollow sleeve which faces the injection device when the injection device is connected to the filling adapter, i.e. when the injection device is brought into engagement with the second connecting port of the adapter element. The interaction of the plunger locking mechanism of the injection device with the hollow sleeve of the filling adapter prevents the plunger from being moved relative to the injection solution receptacle of the injection device and the filling adapter. As a result, an inadvertent contact between the plunger, i.e. a distal tip of the plunger, and the distal tip of the filling adapter cannula can reliably be prevented.

The plunger locking mechanism may comprise a lever element which is displaceable between an active position and an inactive position. When being arranged in its active position, the lever element may interact with the plunger and the hollow sleeve of the filling adapter so as to prevent the plunger from being moved from its filling position in a distal direction when the injection device is connected to the filling adapter. To the contrary, when being arranged in its inactive position, the lever element may allow a movement of the plunger from its filling position in a distal direction when the injection device is not connected to the filling adapter. In a preferred embodiment, the lever element is rotatable around a rotational axis between its active position and its inactive position. For example, the lever element may be provided with a hinge which rotatably attaches the lever element to a rotational axis provided on a housing of the injection device.

The lever element of the plunger locking mechanism may comprise at least one foot element which is adapted to be contacted by the filling adapter when the injection device is connected to the filling adapter, in order to maintain the lever element in its active position. Preferably, the foot element of the plunger locking mechanism faces the filling adapter and is contacted by the locking rim of the hollow sleeve which faces the injection device when the injection device is connected to the filling adapter. Due to the interaction between the locking rim of the hollow sleeve and the foot element, the lever element may be pushed in a direction substantially parallel to a longitudinal axis of the plunger into contact with the plunger and thus held in its active position. In a preferred embodiment of the injection solution transferring system, the lever element is provided with two foot elements which extend substantially parallel to each other.

In particular, the lever element of the plunger locking mechanism may comprise a stop device which is adapted to contact an abutment surface of the plunger when the lever element is arranged in its active position, in order to prevent the plunger from being moved from its filling position in a distal direction when the injection device is connected to the filling adapter. In other words, due to the interaction between the locking rim of the hollow sleeve and the foot element, the lever element may be pushed in a direction substantially parallel to a longitudinal axis of the plunger so that the stop device provided on the lever element abuts against the abutment surface of the plunger. As a result, the lever element is held in its active position and, simultaneously, movement of the plunger from its filling position in a distal direction is prevented.

To the contrary, as soon as the filling adapter is detached from the injection device, the filling adapter, i.e. the locking rim of the hollow sleeve, no longer contacts the foot element of the lever element. Hence, when a pressing force is applied to the plunger so as to displace the plunger in a distal direction within the injection solution receptacle of the injection device, the lever element is displaced into its inactive position. In particular, the lever element is rotated around its rotational axis from its active position into its inactive position and hence out of the way of the plunger. As a result, the displacement of the plunger is no longer hindered.

A proximal portion of the plunger may, at least in sections, extend further in a direction substantially perpendicular to the longitudinal axis of the plunger than a distal portion of the plunger. As a result, a shoulder which defines the abutment surface of the plunger may be formed in a transition region between the distal portion and the proximal portion of the plunger. For example, the abutment surface of the plunger may be defined by an outer portion of a distal end face of the proximal plunger portion which protrudes from an outer circumferential surface of the distal plunger portion.

The plunger locking mechanism may also comprise a retention device which is adapted to interact with the at least one foot element of the lever element, in order to prevent the at least one foot element from becoming disengaged from the filling adapter when the lever element, by the interaction between the filling adapter and the foot element, is maintained in its active position. In particular, the retention device is adapted to prevent that the foot element slips around the locking rim of the hollow sleeve and hence disengages from the filling adapter. The retention device may, for example, be provided in a housing of the injection device and may be designed in the form of a retention rib which prevents the foot element of the lever element to deform away from the plunger in a direction substantially perpendicular to the longitudinal axis of the plunger.

An injection solution transferring system wherein the injection device comprises a plunger locking mechanism may be claimed independently from the above described filling adapter design. In particular, an independent claim may be formulated which is directed to an injection solution transferring system which comprises an injection device adapted to be filled with an injection solution from a syringe and a filling adapter for connecting the syringe to the injection device. In said injection solution transferring system, the injection device further comprises a plunger locking mechanism which is adapted to interact with the filling adapter, in particular a hollow sleeve of the filling adapter, so as to prevent the plunger of the injection device from being moved from its filling position in a distal direction, when the injection device is connected to the filling adapter. The plunger locking mechanism of said injection solution transferring system may be designed as described above.

A preferred embodiment of the invention now will be described in greater detail with reference to the appended schematic drawings, wherein:

FIG. 1 shows an exploded view of an injection solution transferring system which comprises a filling adapter and injection device,

FIG. 2 shows a three-dimensional view of the filling adapter and the injection device in a connected state,

FIG. 3 shows a longitudinal section of the filling adapter being connected to the injection device,

FIGS. 4 and 5 show detailed three-dimensional views of a hollow sleeve of the filling adapter,

FIGS. 6 and 7 show detailed three-dimensional views of an adapter element of the filling adapter,

FIG. 8 shows the arrangement of the adapter element in the hollow sleeve of the filling adapter,

FIG. 9 shows a three-dimensional longitudinal cut view of the adapter element and a cannula of the filling adapter,

FIG. 10 shows a longitudinal section of the adapter element and the cannula of the filling adapter,

FIG. 11 shows a detailed view of an injection solution receptacle of the injection device,

FIG. 12 shows a detailed view of the plunger of the injection device,

FIG. 13 shows a detailed view of a tip element of the plunger,

FIG. 14 shows the arrangement of the cannula of the filling adapter relative to the plunger of the injection device when the filling adapter is connected to the injection device,

FIG. 15 shows the interaction between the guiding rib of the hollow sleeve with the injection solution receptacle of the injection device,

FIGS. 16 to 18 show detailed three-dimensional views of a first housing element of the injection device,

FIGS. 19a and 19b show the interaction between the plunger and the first housing element,

FIGS. 20 and 21 show detailed three-dimensional views of the second housing element of the injection device,

FIG. 22 shows the assembly of the second housing element,

FIG. 23 shows the attachment of the injection solution receptacle to the second housing element,

FIGS. 24 and 25 show the interaction between the first and the second housing element,

FIG. 26 shows the interaction between the plunger and the second housing element,

FIGS. 27 and 28 show detailed three-dimensional views of a lever element of a plunger locking mechanism which prevents the plunger of the injection device from being moved from a filling position in a distal direction when the injection device is connected to the filling adapter,

FIG. 29 shows the lever element of the plunger locking mechanism in an active position,

FIG. 30 shows the lever element of the plunger locking mechanism in an inactive position,

FIG. 31 shows the injection solution transferring system with the filling adapter being connected to the injection device, with one part of the second housing element removed and with the lever element of the plunger locking mechanism in its active position,

FIG. 32 shows the assembly of the lever element of the plunger locking mechanism in the second housing element,

FIGS. 33a to 33d show the use of the injection solution transferring system upon filling the injection device with an injection solution from a syringe, and

FIGS. 34a to 34d show the use of the injection device upon administering an injection solution to a patient.

FIGS. 1 and 2 show an injection solution transferring system 100 which comprises an injection device 10 and a filling adapter 12. The filling adapter 12 serves to connect a syringe 14 containing an injection solution to the injection device 10 for filling the injection device 10 with the injection solution from the syringe 14 as shown in FIGS. 33a to 33d and as will be described further below. The syringe 14 is designed in the form of a pre-filled syringe 14 which contains an injection solution for intraocular use.

The filling adapter 12 comprises a hollow sleeve 16 which is shown in greater detail in FIGS. 4 and 5. The hollow sleeve 16 made of a coloured plastic material, for example Polycarbonate/Acrylnitril Butadien Styrol (PC-ABS) and is provided with an inner lumen which is dimensioned so as to allow the insertion of at least a distal portion of the syringe 14 at one end and of at least a distal portion of the injection device 10 at an opposing end. In the exemplary embodiment of a filling adapter 12 shown in the drawings, the hollow sleeve 16 has a substantially circular hollow cylindrical shape and the lumen extending therethrough has a substantially circular cross-sectional shape.

The filling adapter 12 further comprises an adapter element 18 which is accommodated within the hollow sleeve 16 and which comprises a first connecting port 20 and a second connecting port 22. The adapter element 18 may, for example, be made of polycarbonate and is shown in greater detail in FIGS. 6 to 10. As shown in particular in FIG. 8, the adapter element 18 is provided with two retention shoulders 23 which protrude from an outer circumferential surface of the adapter element 18 in opposing directions. Each retention shoulder 23 interacts with a pair of complementary crush ribs 24 protruding from an inner circumferential surface of the hollow sleeve 16 in order to fix the adapter element 18 in its position within the hollow sleeve 16. The retention shoulders 23 and the complementary crush ribs 24 create an interference fit so as to reliably fix the adapter element 18 in its position within the hollow sleeve 16.

The first connecting port 20 of the adapter element 18 is adapted to be connected to the syringe 14, i.e. a distal end of the syringe 14, when the filling adapter 12 is connected to the syringe 14 as shown in FIGS. 33a to 33c . As becomes apparent in particular from FIG. 10, the first connecting port 20 of the adapter element 18 forms a female Luer taper 25 which is adapted to interact with a male Luer taper provided at the distal end of the syringe 14 in order to establish a fluid-tight connection between the syringe 14 and the adapter element 18. The second connecting port 22 of the adapter element 18 is adapted to be connected to the injection device 10.

The adapter element 18 is provided with a through-opening 26 extending therethrough in a direction substantially parallel to a longitudinal axis L1 of the filling adapter 12, see in particular FIG. 10. A cannula 27 protrudes from the second connecting port 22 of the adapter element 18 and is arranged in fluid communication with the through-opening 26 extending through the adapter element 18, see in particular FIGS. 9 and 10. The cannula 27 is made of stainless steel. The hollow sleeve 16 of the filling adapter 12, however, extends beyond a distal tip of the cannula 27. As a result, a user is protected from the cannula 27 during handling of the filling adapter 12.

The adapter element 18 serves to establish a fluid connection between the syringe 14 and the injection device 10, i.e. when the syringe 14 is connected to the first connecting port 20 of the adapter element 18 and the injection device 10 is connected to the second connecting port 22 of the adapter element 18 as shown in FIG. 33a , injection solution contained in the syringe 14 may be transferred into the injection device 10 by manually pushing a plunger 28 of the syringe 14 as shown in FIGS. 33b and 33c so as to expel the injection solution from the distal end of the syringe 14 into the through-opening 26 provided in the adapter element 18 and further via the cannula 27 into an injection solution receptacle 30 of the injection device 10.

As becomes apparent in particular from FIGS. 4 and 5, the hollow sleeve 16 of the filling adapter 12, in the region of a first end which faces the syringe 14 when the syringe 14 is brought into engagement with the first connecting port 22 of the adapter element 18, the hollow sleeve 16 comprises at least one resilient clip 32 which is adapted to engage with a collar 34 of the syringe 14 when the syringe 14 is brought into engagement with the first connecting port 20 of the adapter element 18, see FIGS. 33a and 33b . In the embodiment of a hollow sleeve 16 shown in the drawings, the hollow sleeve 16 is provided with two resilient clips 32. Each resilient clip 32 comprises an arm 36 which extends in a recess 38 provided in the hollow sleeve 16 substantially parallel to the longitudinal axis L1 of the filling adapter 12 in the direction of the first end of the hollow sleeve 16. A latching nose 40 protrudes from an inner surface of the arm 36 in the region of a free end of the arm 36.

When the syringe 14 is brought into engagement with the first connecting port 20, due to the interaction with the collar 34 of the syringe 14, the resilient clip 32 is bent outwards. However, as soon as the syringe 14 has reached its final position with respect to the adapter element 18, i.e. when the distal tip of the syringe 14 is connected to the first connecting port 20 of the adapter element 18 and the syringe 14 assumes the position relative to the hollow sleeve 16 which is shown in FIG. 33b , the resilient clip 32 resumes its original position substantially parallel to the longitudinal axis L1 of the filling adapter 12 such that the latching nose 40 comes into engagement with an end face of the collar 34 of the syringe 14. As a result, the syringe 14 is firmly connected to the hollow sleeve 16.

In the region of its first end, the hollow sleeve 16 at its outer circumferential surface is provided with two first gripping structures 42 each of which is designed in the form of a nub array. The first gripping structure simplifies the handling of the filling adapter 12 during connecting the syringe 14 to the filling adapter 12. Further, the hollow sleeve 16, in the region of its first end and the region of a second end which faces the injection device 10 when the injection device 10 is brought into engagement with the second connecting port 22 of the adapter element 18, has an outer diameter which is larger than an outer diameter of the hollow sleeve 16 in an intermediate section arranged between the first and the second end. Such a design of the hollow sleeve 16 further simplifies the gripping and thus the handling of the filling adapter 12.

As shown in in FIG. 11, the injection solution receptacle 30 of the injection device 10 is designed in the form of an inner injection solution receptacle 30 which is contained within a protective outer barrel 44. The inner injection solution receptacle 30 and the protective outer barrel 44 are formed integral with each other and are made of a sterile plastic material. In the region of its proximal end, the protective outer barrel 44 is provided with a flange element 46. A distal end of the injection solution receptacle 30 is provided with a male Luer taper 48 which interacts with a female Luer taper 50 provided on the second connecting port 22 of the adapter element 18 of the filling adapter 12 when the filling adapter 12 is connected to the injection device 10 as shown in FIGS. 2 and 3. By means of the Luer tapers 48, 50, a fluid-tight connection can be established between the distal end of the injection solution receptacle 30 and the adapter element 18 of the filling adapter 12.

As further becomes apparent from FIG. 11, the outer barrel 44 of the injection device 10, in the region of its distal end, is provided with a Luer thread 52. The Luer thread 52 interacts with a complementary Luer thread 54 provided at an outer circumference of the second connecting port 22 of the adapter element 18, see FIGS. 6 and 8 to 10, when the filling adapter 12 is connected to the injection device 10 as shown in FIGS. 2 and 3. As a result, also a reliable connection between the outer barrel 44 of the injection device 10 and the adapter element 18 of the filling adapter 12 can be effected.

In order to simplify the handling of the filling adapter 12 during bringing the injection device 10 into engagement with the second connecting port 22 of the adapter element 18, the hollow sleeve 18, in the region of a second end which faces the injection device 10 when the injection device 10 is brought into engagement with the second connecting port 22 of the adapter element 18, at its outer circumferential surface is provided with a second gripping structure 56. The second gripping structure 56 is designed in the form of two gripping rib arrays with individual gripping ribs extending substantially parallel to the longitudinal axis L1 of the filling adapter 12.

Further, as shown in FIG. 15, the hollow sleeve 16 is provided with longitudinal guiding ribs 58 which protrude from the inner circumferential surface of the hollow sleeve 16 and which extend substantially parallel to the longitudinal axis L1 of the filling adapter 12. The guiding ribs 58 serve to guide the injection device 10 into engagement with the second connecting port 22. The guiding function of the guiding ribs 58 prevents the cannula 27 from contacting the injection solution receptacle 30 of the injection device 10 upon connecting the filling adapter 12 to the injection device 10. The hollow sleeve 16 and the longitudinal guiding ribs 58 are designed, i.e. shaped and dimensioned, in such a manner that a close sliding fit is generated between the guiding ribs 58 and an outer surface of the outer barrel 54 of the injection device 10.

Turning back to FIGS. 9 and 10, the through-opening 26 extending through the adapter element 18 comprises an inlet section 26 a which is arranged adjacent to the first connecting port 20. In use of the filling adapter 12, injection solution expelled from the syringe 14 thus enters the through-opening 26 via its inlet section 26 a which has a flow cross-section which decreases in a direction of flow of the injection solution expelled from the syringe 14. Further, the through-opening 26 comprises an intermediate section 26 b which, in the direction of flow of the injection solution expelled from the syringe 14 during use of the filling adapter 12, is arranged downstream of the inlet section 26 a. The intermediate section 26 b of the through-opening 26 has a substantially constant flow cross-section which substantially corresponds to the smallest flow cross-section of the inlet section 26 a adjacent to the intermediate section 26 b. Finally, the through-opening 26 comprises a receiving section 26 c which, in the direction of flow of the injection solution expelled from the syringe 14 during use of the filling adapter 12, is arranged downstream of the intermediate section 26 b, i.e. adjacent to the second connecting port 22. The receiving section 26 c has a flow cross-section that is larger than the flow cross-section of the intermediate section 26 b.

As further becomes apparent from FIGS. 9 and 10, the cannula 27 extends into at least a portion of the intermediate section 26 b of the through-opening 26 so that the intermediate section 26 b of the through-opening 26 or a portion thereof defines a cannula receiving bore of the adapter element 18 wherein a proximal end of the cannula 27 is fixed. The cannula 27 is received in the cannula receiving bore with a close slide fit. In addition, the cannula 27 is provided with bevelled ends. This design of the cannula 27 and the cannula receiving bore minimizes the generation of wear particles upon attaching the cannula 27 in the cannula receiving bore. The final bonding between the adapter element 18 and the cannula 27 is effected by means of a UV-cured glue. The cannula 27 extends from the intermediate section 26 b of the through-opening 26, through the receiving section 26 c of the through-opening 26 and the second connecting port 22 so as to protrude from the second connecting port 22. The receiving section 26 c of the through-opening 26, the second connecting port 22 and the hollow sleeve 16 of the filling adapter 12 define a concentric arrangement around the cannula 27, see in particular FIG. 3.

As shown in particular in FIG. 8, the adapter element 18 is provided with two retention shoulders 60 which protrude from an outer circumferential surface of the adapter element 18 in opposing directions in the region of the inlet section 26 a and the intermediate section 26 b of the through-opening 26 extending through the adapter element 18.

When the filling adapter 12 is connected to the injection device 10, the cannula 27 extends into the injection solution receptacle 30 of the injection device 10, i.e. a distal tip of the cannula 27 is arranged at a distance from the distal end of the injection solution receptacle 30 within the interior of the injection solution receptacle 30, see in particular FIG. 3. As a result, upon transferring injection solution from the syringe 14 to the injection device 10, injection solution exiting the syringe 14, via the cannula 27, is supplied to the injection solution receptacle 30 of the injection device 10 not in the region of the distal end of the injection solution receptacle 30, but at a position arranged at a distance from the distal end of the injection solution receptacle 30 within the interior of the injection solution receptacle 30.

By simply holding the filling adapter 12 and the injection device 10 in an upright position with the longitudinal axis L1 of the filling adapter 12 and a longitudinal axis L2 of the injection device 10 being oriented substantially vertically and with the distal end of the injection device 10 facing downwards as shown in FIGS. 33a to 33c , a gravity-driven flow of the injection solution from the distal tip of the cannula 27 downwards in a direction of the distal end of the injection solution receptacle 30 and further in the direction of the adapter element 18 can be induced. A part of the injection solution which is expelled from the distal tip of the cannula 27 and which in a gravity-driven manner flows back in the direction of the adapter element 18 is received in the receiving section 26 c of the opening 26 provided in the adapter element 18. Gas bubbles which are entrapped within the injection solution and hence transferred from the syringe 14 to the injection solution receptacle 30 together with the liquid phase of the injection solution are entrained with this gravity-driven flow and, due to the higher specific density of the liquid phase of the injection solution, are forced in the direction of the distal end of the injection solution receptacle 30 and further in the direction of the adapter element 18.

Finally, the adapter element 18 is provided with a venting device 64 which is adapted to vent gas introduced from the syringe 14 into the injection device 10, i.e. the injection solution receptacle 30 of the injection device 10, via the through-opening 26 and the cannula 27 into the ambient. The venting device thus allows entrapped gas bubbles, in particular air bubbles, that are conveyed from the distal tip of the cannula 27 back to the adapter element 18 by the above described gravity-driven flow of the injection solution to be expelled into the ambient. The filling adapter 12 thus allows a gas free filling of the injection device 10 with the injection solution. As a result, manually expelling entrapped gas from the syringe 14 prior to connecting the syringe 14 to the filling adapter 12 can be dispensed with. Furthermore, an accurate and reliable preparation of a desired dose of the injection solution within the injection device 10 is made possible.

The venting device 64 comprises two radial bores 66 connecting the through-opening 26 extending through the adapter element 18 to the ambient. In particular, the radial bores 66 connect the receiving section 26 c of the through-opening 26 to an outer circumferential surface of the adapter element 18 and hence to the ambient. In the embodiment of a filling adapter 18 shown in the drawings, the radial bores 66 of the venting device 64 extend coaxially from an outer circumferential surface of the adapter element 18 to the receiving section 26 c of the through-opening 26 so as to connect the receiving section 26 c of the through-opening 26 to the ambient. In order to ensure that gas bubbles entrapped in the injection solution can be vented to the ambient as desired without expelling a substantial amount of the liquid phase of the injection solution to the ambient, the flow cross-section, i.e. the diameter of the radial bores 66 is be selected in dependence on the physical properties, in particular the specific density, the viscosity and the surface tension of the injection solution to be transferred from the syringe 14 to the injection device 10.

In order to ensure proper functioning of the venting device 64, the retention shoulders 23 protrude from the outer circumferential surface of the adapter element 18 in the region of the inlet section 26 a and the intermediate section 26 b of the through-opening 26 extending through the adapter element 18. Such a configuration ensures that, in the region of the receiving section 26 c of the through-opening 26, an air gap 68 is present between the outer circumferential surface of the adapter element 18 and the inner circumferential surface of the hollow sleeve 16 which allows an unhindered exit of gas from receiving section 26 c via the radial bores 66 of the venting device 64.

The injection device 10 of the injection solution transferring system 100 further comprises a plunger 70 which is depicted in greater detail in FIG. 12. In the embodiment of an injection device 10 shown in the drawings, the plunger 70 is made of polycarbonate. At least a portion of the plunger 70 is slidably received within the injection solution receptacle 30 of the injection device 10. The plunger 70 is displaceable relative to the injection solution receptacle 30 in a distal direction along a longitudinal axis of the plunger 70 in order to expel injection solution contained in the injection solution receptacle 30 of the injection device 10 from the injection solution receptacle 30. At its proximal end which protrudes from the injection solution receptacle 30 in a proximal direction, the plunger 70 carries an actuation button 72 which may be depressed by a user in order to displace the plunger 70 relative to the injection solution receptacle 30 in the distal direction along the longitudinal axis of the plunger 70.

At its distal end, the plunger 70 is provided with a tip element 74 which is attached to a plunger rod 76, see FIG. 13. A coupling between the plunger rod 76 and the tip element 74 is effected by the interaction of a tip barb 78 provided at a distal end of the plunger rod 76 with a barb receptacle 80 of the tip element 74. Further, the tip element 74 is provided with a sealing element 82 which is provided in the region of an outer circumferential surface of the tip element 74 and which sealingly interacts with an inner circumferential surface of the injection solution receptacle 30.

The plunger 70 of the injection device 10 can be arranged in a filling position as shown in FIGS. 33a to 33d . When the plunger 70 is arranged in its filling position and the injection device 10 is engaged with the second connecting port 22 of the adapter element 18 of the filling adapter 12, a distal tip of the plunger 70, i.e. a distal end face of the tip element 74 provided at the distal tip of the plunger 70, is disposed at a desired close distance D from the distal tip of the cannula 27 of the filling adapter 12, see FIG. 14. For example, the injection device 10 and the filling adapter 12 may be designed so as to set the distance D between the distal tip of the plunger 70 and the distal tip of the cannula 27 to approximately 1.5 mm+/−0.5 mm. By arranging the distal tip of the plunger 70 and the distal tip of the cannula 27 at a close distance, the injection solution supplied to the injection solution receptacle 30 via the cannula 27 is reliably forced to flow in the direction of the venting device 64. As a result, air-free filling of the injection solution receptacle 30 with the injection solution can be ensured.

Finally, the hollow sleeve 16 is provided with two observing windows 83 for observing the filling of the injection device 10 with the injection solution from the syringe 14. The observing windows 83 allow an unhindered view of interior of the injection device 10 and the distal tip of the cannula 27.

The plunger 70 is displaceably received in a housing 84 of the injection device 10 which comprises a first housing element 86 depicted in greater detail in FIGS. 16 to 19 and a second housing element 88 depicted in greater detail in FIGS. 20 to 23. Both the first and the second housing element 86, 88 are made of polycarbonate/acrylnitril butadien styrol, but have a different colour. The first housing element 86 is provided with a plunger through-hole 90 which receives the plunger rod 76 so that the plunger 70 is displaceable in a direction along its longitudinal axis relative to the first housing element 86. Guiding elements 92 are provided on the first housing element 86 so as to protrude into the plunger through-hole 90. When the plunger 70, i.e. the plunger rod 76, is received in the plunger through-hole 90 of the first housing element 86, each guiding element 92 engages with a guiding channel 94 which provided in a circumferential surface of the plunger 70, i.e. the plunger rod 76, and which extends along the longitudinal axis of the plunger 70, see in particular FIGS. 19a and 19 b.

For assembling the plunger 70 to the first housing element 86, assembly channels 96 are provided in the outer circumferential surface of the plunger rod 76 which branch of from the guiding channels 94 in a distal region thereof and extend substantially perpendicular to the guiding channels 94 in a circumferential direction of the plunger rod 76. Upon assembling the plunger 70 to the first housing element 86, the guiding elements 92 are brought into engagement with the assembly channels 96. Thereafter, the plunger 70 is rotated until the guiding elements 92 are received in the guiding channels 94 in a guiding manner, see FIGS. 19a and 19 b.

In order to simplify the handling of the injection solution transferring system 100, the injection device 10 is delivered with the plunger 70 being arranged in its filling position which corresponds to a proximal end position of the plunger 70. A plunger positioning mechanism 98 prevents that the plunger 70 can be moved further in a proximal direction relative to the injection solution receptacle 30 than into its proximal end position, i.e. its filling position. The plunger positioning mechanism 98, however, allows a movement of the plunger 70 relative to the injection solution receptacle 30 from its filling position in a distal direction. Specifically, the plunger positioning mechanism 98 is defined by a distal end face 102 of the guiding channels 94 which are provided in the circumferential surface of the plunger rod 78 and the guiding elements 92 provided on the first housing element 86. When the plunger 70 is arranged in its proximal end position which corresponds to its filling position, the guiding elements 90 abut against the distal end faces 102 of the guiding channels 94. The interaction between the distal end faces 102 of the guiding channels 94 and the guiding elements 92 then prevents a further movement of the plunger 70 in the proximal direction and hence define the proximal end position, i.e. the filling position of the plunger 70.

The second housing element 88 comprises two identical parts, see FIGS. 20 and 21, each of which comprises an interference pin 104 and an interference receptacle 106. The two housing parts of the second housing element 88 are assembled by bringing the interference pins 104 into engagement with the respective interference receptacles 106 as shown in FIG. 22. For aligning the parts of the second housing element 88 relative to each other upon assembly, alignment pins 108 are provided which, upon connecting the parts of the second housing element 88, are received in respective alignment receptacles 110. The injection solution receptacle 30 and the protective outer barrel 44 are connected to the second housing element 88 via the flange element 46 which extends from the outer barrel 44 at a proximal end thereof. Specifically, the flange elements 46 is received in a suitably shaped and dimensioned receptacle 112 of the second housing element 88, see FIG. 23.

As shown in particular in FIG. 26, the second housing element 88 is provided with a plunger guide 114 which constrains the plunger rod 76 so that the plunger 70 is prevented from rotating relative to the second housing element 88. A first drag mechanism 116 is adapted to exert a retaining force which retains the plunger 70 in its current position relative to second housing element 88. The first drag mechanism 116 thus prevents an unintentional displacement of the plunger 70 relative to the injection solution receptacle 30 so that active manual actuation of the plunger 70, for example by the application of a pressing force to the actuation button 72, is necessary for displacing the plunger 70 relative to the injection solution receptacle 30. The first drag mechanism 116 comprises a resilient drag element 118 which is provided on the second housing element 88. The resilient drag element 118 exerts a resilient retaining force on the plunger 70, i.e. the resilient drag element 118 is resiliently urged out of a rest position into a biasing position by an interaction with the plunger 70 and, due to its resiliency, applies a resilient reaction force on the plunger 70 which retains the plunger 70 in its current position. Specifically, the resilient drag element 118 interacts with a drag rib 120 which is provided on the outer circumferential surface of the plunger rod 76 and which extends substantially parallel to the longitudinal axis of the plunger 70.

The injection device 10 further comprises a plunger locking mechanism 122 which interacts with the filling adapter 12, i.e. the hollow sleeve 16 of the filling adapter 12, so as to prevent the plunger 70 of the injection device 10 from being moved from its filling position relative to the injection solution receptacle 30 in a distal direction, i.e. in the direction of the distal tip of the cannula 27, when the injection device 10 is connected to the filling adapter 12. The plunger locking mechanism 122 serves to prevent an inadvertent contact between the plunger 70, i.e. the distal tip of the plunger 70, and the distal tip of the cannula 27. The functioning of the plunger locking mechanism 122 now will be described in greater detail with reference to FIGS. 27 to 32.

Specifically, the plunger locking mechanism 122 comprises a lever element 124, see FIGS. 27 and 28, which is displaceable within the second housing element 88 between an active position which is depicted in FIGS. 29 and 31 and an inactive position depicted in FIG. 30. When being arranged in its active position, the lever element 124 interacts with the plunger 70 and the hollow sleeve 16 of the filling adapter 12 so as to prevent the plunger 70 from being moved from its filling position in a distal direction when the injection device 10 is connected to the filling adapter 12. To the contrary, when being arranged in its inactive position, the lever element 124 allows a movement of the plunger 70 from its filling position in a distal direction when the injection device 10 is not connected to the filling adapter 12. The lever element 124 is mounted within the second housing element 88 so as to be rotatable between its active position and its inactive position. Specifically, the lever element 124 is provided with a hinge 126 which rotatably attaches the lever element 124 to a rotational axis 128 provided on the second housing element 88.

The lever element 124 further comprises a pair of foot elements 130 which extend substantially parallel to each other and which are contacted by the filling adapter 12 when the injection device 10 is connected to the filling adapter 12, in order to maintain the lever element 124 in its active position. In particular, as shown in FIG. 29, the foot elements 130 face the filling adapter 12 and are contacted by a locking rim 132 of the hollow sleeve 16 which faces the injection device 10 when the injection device 10 is connected to the filling adapter 12. Due to the interaction between the locking rim 132 of the hollow sleeve 16 and the foot elements 130, the lever element 124 is pushed in a proximal direction substantially parallel to the longitudinal axis of the plunger 70 into contact with the plunger 70 and thus held in its active position shown in FIGS. 29 and 31.

The lever element 124 comprises a stop device 134 which comprises two tabs extending from a proximal end face of the lever element 124. Further, a proximal portion of the plunger 70 extends further in a direction substantially perpendicular to the longitudinal axis of the plunger 70 than a distal portion of the plunger 70. As a result, a shoulder which defines an abutment surface 136 is formed in a transition region between the distal portion and the proximal portion of the plunger 70. Specifically, the abutment surface 136 is defined by an outer portion of a distal end face of the proximal plunger portion which protrudes from an outer circumferential surface of the distal plunger portion. When the lever element 124 is arranged in its active position as shown in FIG. 29, the two tabs of the stop device 134 abut against the abutment surface 136 of the plunger 70. As a result, the lever element 124 is held in its active position and, simultaneously, movement of the plunger 70 from its filling position in a distal direction is prevented.

The plunger locking mechanism 122 also comprises a retention device 138 which interacts with the foot elements 130 of the lever element 124, in order to prevent that the foot elements 130 disengage from locking rim 132 of the filling adapter 12 when the lever element 124, by the interaction between the locking rim 132 and the foot elements 130, is maintained in its active position, see FIGS. 20 and 32. In particular, the retention device 138 prevents that the foot elements 130 slip around the locking rim 132 of the hollow sleeve 16 and hence disengages from the filling adapter 12 when the lever element 124 is pushed into engagement with the plunger 70. The retention device is provided in the second housing element 88 and is designed in the form of a retention rib which prevents that the foot elements 130 of the lever element 124 deform away from the plunger 70 in a direction substantially perpendicular to the longitudinal axis of the plunger 70.

After completion of the transfer of the injection solution from the syringe 14 to the injection solution receptacle 30 of the injection device 10 with the plunger 70 being arranged in its filling position as described above and as shown in FIGS. 33a to 33c , the filling adapter 12 and the syringe 14 are detached from the injection device 10 by disengaging the male Luer taper 48 provided at the distal end of the injection solution receptacle 30 from the female Luer taper 50 provided on the second connecting port 22 of the adapter element 18 and by disengaging the Luer thread 52 provided at the distal end of the outer barrel 44 from the complementary Luer thread 54 provided at the second connecting port 22, see FIG. 33 d.

As soon as the filling adapter 12 is detached from the injection device 10, the filling adapter 12, i.e. the locking rim 132 of the hollow sleeve 16, no longer contacts the foot elements 130 of the lever element 124. Hence, when a pressing force is applied to the plunger 70 so as to displace the plunger 70 in a distal direction within the injection solution receptacle 30 of the injection device 10, the lever element 124 is displaced into its inactive position shown in FIG. 30. In particular, the lever element 124 is rotated around its rotational axis 128 from its active position into its inactive position and hence out of the way of the plunger 70. As a result, the displacement of the plunger 70 is no longer hindered. Consequently, a needle (not shown in the drawings) can be attached to the injection device 10, for example with the aid of the Luer thread 52 provided at the distal end of the outer barrel 44 and injection device 10 can be operated as will be described further below.

For administering an accurate dose, in particular an accurate micro dose of, for example, 10 μl of the injection solution received within the injection solution receptacle 30 to a patient, in a first step, excess injection solution has to be expelled from the injection solution receptacle 30 by displacing the plunger 70 relative to the injection solution receptacle 30 in the distal direction as shown in FIG. 34a . Thereafter, the desired to dose of the injection solution has to be injected into the patient.

The injection device 10 therefore comprises a first plunger stop mechanism 140 which is adapted to stop a displacement of the plunger 70 relative to the injection solution receptacle 30 in the distal direction at a first dosing position P1, see FIG. 34. Further, the injection device 10 comprises a second plunger stop mechanism 142 which is adapted to stop a displacement of the plunger 70 relative to the injection solution receptacle 30 from the first dosing position P1 in the distal direction at a second dosing position P2, see FIG. 34d . The first and the second dosing position P1, P2 of the plunger 70 are selected in such a manner that the plunger 70, upon being displaced relative to the injection solution receptacle 30 between the first and the second dosing position P1, P2 is adapted to expel a desired dose of the injection solution contained in the injection solution receptacle 30 from the injection solution receptacle 30.

Thus, during use of the injection device 10, a user can expel excess injection solution from the injection solution receptacle 30 by displacing the plunger 70 relative to the injection solution receptacle 30 in the distal direction until the plunger 70 reaches the first dosing position P1. Upon reaching the first dosing position P1, the first plunger stop mechanism stops 140 further displacement of the plunger 70 in the distal direction. Consequently, the user is prevented from expelling too much injection solution from the injection solution receptacle. The residual injection solution contained in the injection solution receptacle can then be administered to a patient by further displacing the plunger 70 in the distal direction until the plunger 70 reaches the second dosing position P2. Upon reaching the second dosing position P2, the second plunger stop mechanism 142 stops further displacement of the plunger 70 in the distal direction and hence prevents that too much injection solution is administered to the patient.

As shown in particular in FIGS. 12, 16 and 18, the first plunger stop mechanism 140 comprises a dosing element 144 which is attached to the plunger 70 and which is adapted to abut against a first dosing surface 146 provided on the first housing element 86. The dosing element 144 also forms a part of the second plunger stop mechanism 142 and, as a part of the second plunger stop mechanism 142, is adapted to abut against a second dosing surface 148 which is also provided on the first housing element 86. The dosing element 144 is formed integral with the plunger 70 and is designed in the form of a rib protrudes from a lower surface of the activation button 72 in the direction of the inner solution receptacle 30.

The first and the second dosing surface 146, 148 extend substantially parallel to each other and parallel to an abutting surface 150 of the dosing element 144 substantially perpendicular to the longitudinal axis of the plunger 70, wherein the second dosing surface 148 is arranged parallel offset relative to the first dosing surface 146 in the distal direction. A distance S between the first and the second dosing surface 146, 148 in the distal direction corresponds to a desired travel distance of the plunger 70 in the distal direction between the first and the second dosing position P1, P2, see in particular FIG. 18. Hence, the distance S between the first and the second dosing surface 146, 148 in the distal direction sets the desired injection solution dose to be expelled from the injection solution receptacle 30 upon displacing the plunger 70 from the first to the second dosing position P1, P2.

Further, the first and the second dosing surface 146, 148 are arranged offset relative to each other in a circumferential direction of the plunger 70. Specifically, the second dosing surface 148 is defined by a bottom surface of a recess 152 formed in the first dosing surface 146 provided on the first housing element 86.

When the plunger 70, during use of the injection device 10, is moved from its filling position shown in FIG. 34a in the distal direction, the abutting surface 150 of the dosing element 144 abuts against the first dosing surface 146 when the plunger 70 reaches the first dosing position P1 as depicted in FIG. 34b . The interaction of the dosing element 144 with the first dosing surface 146 prevents the plunger from being displaced further in the distal direction. Hence, the first plunger stop mechanism 140 provides a hard stop for the plunger 70 at the first dosing position P1. The injection device 10 therefore further comprises a plunger releasing mechanism 154 which is adapted to deactivate the first plunger stop mechanism 140 in order to release the plunger 70 and to thus allow a displacement of the plunger 70 relative to the injection solution receptacle 30 from the first dosing position P1 in the distal direction, i.e. in the direction of the second dosing position P2.

The plunger releasing mechanism 154 is adapted to allow a movement of the first dosing surface 146 relative to the dosing element 144, i.e. relative to the plunger 70, in order to disengage the dosing element 144 from the first dosing surface 146. Specifically, the plunger releasing mechanism 154 is adapted to allow a rotational movement of the first dosing surface 146 relative to the dosing element 144, i.e. relative to the plunger 70, in order to disengage the dosing element 144 from the first dosing surface 146. In order to effect the rotational movement of the first dosing surface 146 relative to the dosing element 144, the first housing element 86 which carries the first and the second dosing surface 146, 148 is designed so as to be manually rotatable relative to the second housing element 88, see FIG. 34c . Since the plunger 70 is prevented from rotating relative to the second housing element 88 by means of the plunger guide 114, a rotation of the first housing element 86 relative to the second housing element 88 inevitably results in a rotation of the first housing element 86 relative to the plunger 70.

In order to be rotatable relative to the second housing element 88 in a guided manner, the first housing element 86 is provided with a retaining recess 156, see FIGS. 17, 18 and 24, which receives a retaining element 158 formed on the second housing element 88, see FIG. 20. Further, in order to simplify the handling of the plunger releasing mechanism 154, the first housing element 86, in the region of its outer surface, is provided with a gripping structure 159. The gripping structure 159 is designed in the form of a gripping rib array with individual gripping ribs extending substantially in a direction along the longitudinal axis of the plunger 70.

The rotation amount of the first housing element 86 relative to the second housing element 88 and hence relative to the plunger 70 is set such that the recess 152 formed in the first dosing surface 146 is brought into alignment with the dosing element 144 protruding from the activation button 72 of the plunger 70. The plunger releasing mechanism 154 thus is adapted to displace the first and the second dosing surface 146, 148 in the circumferential direction of the plunger 70, in order to disengage the dosing element 144 from the first dosing surface 146 and to simultaneously align the second dosing surface 148 with the dosing element 144.

In order to ensure that a user, upon activating the plunger releasing mechanism 154, rotates the first housing element 86 relative to the second housing element 88 and the correct direction and by the correct rotation amount that is necessary to disengage the dosing element 144 from the first dosing surface 146 and to simultaneously align the second dosing surface 148 with the dosing element 144, the plunger releasing mechanism 154 comprises a marker system 160 which is adapted to indicate an activation of the plunger releasing mechanism 154. The marker system 160 comprises a first marker element 162 which is provided on an outer surface of the first housing element 86. The marker system 160 further comprises a second marker element 164 which is provided on an outer surface of the second housing element 88. The first and the second marker element 162, 164 are arranged on the first and the second housing element 86, 88 in such a position that they are positioned offset relative to each other a circumferential direction of the plunger 70, when the plunger releasing mechanism 154 is not activated, but positioned in alignment with each other, when the plunger releasing mechanism 154 is activated, compare FIGS. 34b and 34 c.

The injection device 10 further comprises a limiting mechanism 166 which is adapted to limit the movement of the first and the second dosing surface 146, 148 for disengaging the dosing element 144 from the first dosing surface 146 and for aligning the dosing element 144 with the second dosing surface 146, see FIGS. 16 and 20. The limiting mechanism 166 comprises a first limiting element 168 which is provided on the first housing element 86 carrying the first and the second dosing surface 146, 148. Further, the limiting mechanism 166 comprises a second limiting element 170 which is provided on the second housing element 88 which remains stationary when the first housing element 86 is rotated in order to deactivate the first plunger stop mechanism 140. The first limiting element 168 abuts against the second limiting element 170 when the dosing element 144, due to the rotation of the first housing element 86 relative to plunger 70, is disengaged from the first dosing surface 146 and aligned with the second dosing surface 148. The limiting mechanism 166 prevents a user of the injection device 10 from excessively rotating the first housing element 86 relative to the second housing element 88. Further, the limiting mechanism 166 provides an haptic feedback to the user that the first plunger stop mechanism 140 has been deactivated.

A second drag mechanism 172 serves to exert a retaining force which retains the first housing element 86 in its current position relative to the second housing element 88. Due to the presence of the second drag mechanism 172, active manual actuation is necessary for rotating the first housing element 86 relative to the second housing element 88. The second drag mechanism 172 thus prevents an unintentional displacement of the first housing element 86 relative to the second housing element 88 and hence an unintentional activation of the plunger releasing mechanism 154. The second drag mechanism 172 comprises a friction element 174 which is provided on the first limiting element 168 of the limiting mechanism 166 and which is adapted to frictionally interact with the retaining element 158 of the second housing element 88.

The injection device 10 further comprises an activation mechanism 176 which is adapted to prevent an activation of the plunger releasing mechanism 154 unless the plunger 70 is arranged at the first dosing position P1 and which is adapted to allow an activation of the plunger releasing mechanism 154 when the plunger 70 is arranged at the first dosing position P1 see FIGS. 12, 16 and 19 a. Specifically, the activation mechanism 176 prevents a rotation of the first housing element 86 relative to the plunger 70 and hence prevents a movement of the dosing element 144 and the first dosing surface 144 relative to each other unless the plunger 70 is arranged at the first dosing position P1.

The activation mechanism 176 comprises the guiding channel 94 which is provided on the circumferential surface of the plunger 70, which extends along the longitudinal axis of the plunger 70 and which receives the guiding element 92 provided on the first housing element 86 in such a manner that the guiding channel 94, upon displacement of the plunger 70 relative to the injection solution receptacle 30, is displaced relative to the guiding element 92. An interaction between the guiding element 92 and opposing side surfaces of the guiding channel 94 prevents a rotation of the plunger 70 and the first housing element 86 relative to each other. The activation mechanism 176 thus fulfills the double function to provide for a guided displacement of the plunger 70 in the direction of its longitudinal axis on the one hand and to simultaneously prevent an unintentional deactivation of the first plunger stop mechanism 154 when the plunger 70 is not arranged at the first dosing position.

The activation mechanism 176 further comprises an activation channel 178 which branches off from the guiding channel 94 and extends in a circumferential direction of the plunger 70 substantially perpendicular to the guiding channel 94. The activation channel 178 receives the guiding element 92 when the plunger 70 is arranged at the first dosing position P1 and the first housing element 86 is rotated relative to the plunger 70. Hence, the first dosing position P1 of the plunger 70 is defined by the position of the activation channel 178 along the longitudinal axis of the plunger 70.

Finally, the plunger releasing mechanism 154 further comprises a locking arrangement 180 which locks the first dosing surface 146 in its position relative to the dosing element 144 after the first dosing surface 146 has been moved relative to the dosing element 144 in order to become disengaged from the dosing element 144, see FIGS. 17, 21 and 25. Specifically, the locking arrangement 180 comprises a resilient locking clip 182 which is provided on the second housing element 88 and which is resiliently urged out of a rest position by the interaction with a locking element 184 provided on the first housing element 86 when the first dosing surface 146 is moved relative to the dosing element 144 so as to become disengaged from the dosing element 144, i.e. when the first housing element 86 is rotated relative to the second housing element 88.

The locking clip 182 deforms back into its rest position after completion of the movement of the first dosing surface 146, i.e. after completion of the rotation of the first housing element 86, and interacts with the locking element 184 so as to lock the first housing element 86 relative to the second housing element 88 and the plunger 70. In particular, the locking clip 182 interacts with the locking element 184 so as to prevent a counter rotation of the first housing element 86 relative to the second housing element 88 and the plunger 70, after the first housing element 86 has been rotated once in order to disengage the first dosing surface 146 from the dosing element 144 and to align the second dosing surface 148 with the dosing element 144. Consequently, the first dosing surface 146 is locked in its position relative to the dosing element 144. The locking arrangement 180 allows the plunger releasing mechanism 154 to be used only once for deactivating the first plunger stop mechanism 140. As a result, reuse of the injection device 10 is prevented.

After completion of the rotational movement of the first housing element 86 relative to the second housing element 88 with the plunger 70 being arranged in its first dosing position P1, the dosing element 144 is aligned with the recess 152 formed in the first dosing surface 146. Consequently, the abutting surface 150 of the dosing element 144 is arranged parallel to the second dosing surface 148 at the distance S. As a result, the plunger 70 can further be displaced from the first dosing position P1 in the distal direction by the distance S into the second dosing position P2, until the dosing element 144, i.e. its abutting surface 150 abuts against the second dosing surface 148, compare FIGS. 34c and 34d . Like the first plunger stop mechanism 140, also the second plunger stop mechanism 142 provides a hard stop for the plunger 70, i.e. prevents the plunger 70 from being displaced relative to the injection solution receptacle 30 from the second dosing position P2 in the distal direction. The dose of the injection solution to be administered to a patient can thus be set in a particularly accurate manner.

LIST OF REFERENCE NUMERALS

injection solution transferring system 100

injection device 10

filling adapter 12

syringe 14

hollow sleeve 16

adapter element 18

first connecting port 20

second connecting port 22

retention shoulders 23

crush ribs 24

female Luer taper (of the first connecting port) 25

through-opening 26

inlet section (of the through-opening) 26 a

intermediate section (of the through-opening) 26 b

receiving section (of the through-opening) 26 c

longitudinal axis (of the filling adapter) L1

longitudinal axis (of the injection device) L2

cannula 27

plunger (of the syringe) 28

injection solution receptacle 30

resilient clip 32

collar (of the syringe) 34

arm (of the resilient clip) 36

recess 38

latching nose (of the resilient clip) 40

first gripping structure 42

outer barrel 44

flange element 46

male Luer taper (of the injection solution receptacle) 48

female Luer taper (of the second connecting port) 50

Luer thread (of the outer barrel) 52

Luer thread (of the second connecting port) 54

second gripping structure 56

guiding ribs 58

venting device 64

radial bore 66

air gap 68

plunger 70

actuation button 72

tip element 74

plunger rod 76

tip barb 78

barb receptacle 80

sealing element 82

distance distal tip plunger/distal tip cannula D

observing windows 83

housing 84

first housing element 86

second housing element 88

plunger through-hole 90

guiding element 92

guiding channel 94

assembly channel 96

plunger positioning mechanism 98

distal end face (of the guiding channel) 102

interference pin 104

interference receptacle 106

alignment pin 108

alignment receptacle 110

receptacle (for receiving flange element) 112

plunger guide 114

first drag mechanism 116

resilient drag element 118

drag rib 120

plunger locking mechanism 122

lever element 124

hinge 126

rotational axis 128

foot elements 130

locking rim 132

stop device 134

abutment surface (of the plunger) 136

retention device 138

first plunger stop mechanism 140

second plunger stop mechanism 142

first dosing position P1

second dosing position P2

dosing element 144

first dosing surface 146

second dosing surface 148

distance first dosing surface/second dosing surface S

abutting surface (of the dosing element) 150

recess 152

plunger releasing mechanism 154

retaining recess 156

retaining element 158

gripping structure 159

marker system 160

first marker element 162

second marker element 164

limiting mechanism 166

first limiting element 168

second limiting element 170

second drag mechanism 172

friction element 174

activation mechanism 176

activation channel 178

locking arrangement 180

resilient locking clip 182

locking element 184 

1. Filling adapter (12) for connecting a syringe (14) containing an injection solution to an injection device (10), the filling adapter (12) comprising: a hollow sleeve (16); an adapter element (18) accommodated within the sleeve (16), wherein the adapter element (18) comprises a first connecting port (20) adapted to be connected to the syringe (14) and a second connecting port (22) adapted to be connected to the injection device (10), and wherein the adapter element (18) is provided with a through-opening (26) extending therethrough; and a cannula (27) protruding from the second connecting port (22) of the adapter element (18), wherein the cannula (27) is arranged in fluid communication with the through-opening (26) extending through the adapter element (18), and wherein the adapter element (18) further is provided with a venting device (64) which is adapted to vent gas introduced from the syringe (14) into the injection device (10) via the through-opening (26) and the cannula (27) into the ambient.
 2. Filling adapter according to claim 1, wherein the first connecting port (20) of the adapter element (18) forms a female Luer taper which is adapted to interact with a male Luer taper provided at a distal end of the syringe (14).
 3. Filling adapter according to claim 1 or 2, wherein the through-opening (26) comprises: an inlet section (26 a) which is arranged adjacent to the first connecting port (20) and which in particular has a flow cross-section which decreases in a direction of flow of the injection solution expelled from the syringe (14) during use of the filling adapter (12); an intermediate section (26 b) which, in the direction of flow of the injection solution expelled from the syringe (14) during use of the filling adapter (12), is arranged downstream of the inlet section (26 a) and which in particular has a substantially constant flow cross-section; and a receiving section (26 c) which, in the direction of flow of the injection solution expelled from the syringe (14) during use of the filling adapter (12), is arranged downstream of the intermediate section (26 b) and which in particular has a flow cross-section that is larger than the flow cross-section of the intermediate section (26 b).
 4. Filling adapter according to claim 3, wherein the cannula (27) extends into at least a portion of the intermediate section (26 b) of the through-opening (26).
 5. Filling adapter according to any one of claims 1 to 4, wherein the venting device (64) comprises at least one radial bore (66) connecting the through-opening (26) extending through the adapter element (18), in particular the receiving section (26 c) of the through-opening (26), to the ambient.
 6. Filling adapter according to any one of claims 1 to 5, wherein the second connecting port (22) of the adapter element (18) forms a female Luer taper (50) which is adapted to interact with a male Luer taper (48) provided at a distal end of an inner injection solution receptacle (30) of the injection device (10) and/or wherein the second connecting port (22) of the adapter element (18), in particular in the region of its outer circumference, is provided with a Luer thread (54) which is adapted to interact with a complementary Luer thread (52) provided at an outer barrel (44) of the injection device (10), in particular in the region of an inner circumference of the outer barrel (44) of the injection device (10).
 7. Filling adapter according to any one of claims 1 to 6, wherein the adapter element (18) is provided with at least one retention shoulder (23) which protrudes from an outer circumferential surface of the adapter element (18), in particular in the region of at least one of the inlet section (26 a) and the intermediate section (26 b) of the through-opening (26) extending through the adapter element (18), and which interacts with a complementary crush rib (24) protruding from an inner circumferential surface of the hollow sleeve (16) in order to fix the adapter element (18) in its position within the hollow sleeve (16).
 8. Filling adapter according to any one of claims 1 to 7, wherein the hollow sleeve (16), in the region of a first end which faces the syringe (14) when the syringe (14) is brought into engagement with the first connecting port (20) of the adapter element (18), comprises at least one resilient clip (32) which is adapted to resiliently engage with a collar (34) of the syringe (14) when the syringe (14) is brought into engagement with the first connecting port (20).
 9. Filling adapter according to any one of claims 1 to 8, wherein the hollow sleeve (16) is provided with at least one longitudinal guiding rib (58) which protrudes from the inner circumferential surface of the hollow sleeve (16) and which is adapted to guide the injection device (10) into engagement with the second connecting port (22) of the adapter element (18), and/or wherein the hollow sleeve (16) is provided with at least one observing window (83) for observing the filling of the injection device (10) with the injection solution from the syringe (14), and/or wherein the hollow sleeve (16) extends beyond a distal tip of the cannula (27).
 10. Injection solution transferring system (100) comprising: an injection device (10) adapted to be filled with an injection solution from a syringe (14); and a filling adapter (12) for connecting the syringe (14) to the injection device (10) according to any one of claims 1 to
 9. 11. Injection solution transferring system according to claim 10, wherein the injection device (10) comprises a plunger (70) which is adapted to be arranged in a filling position wherein a distal tip thereof is disposed at a desired distance (D) from a distal tip of the cannula (27) of the filling adapter (12) when the injection device (10) engaged with the second connecting port (22) of the adapter element (18) of the filling adapter (12).
 12. Injection solution transferring system according to claim 11, wherein the injection device (10) further comprises a plunger locking mechanism (122) which is adapted to interact with the filling adapter (12) so as to prevent the plunger (70) of the injection device (10) from being moved from its filling position in a distal direction when the injection device (10) is connected to the filling adapter (12),
 13. Injection solution transferring system according to claim 12, wherein the plunger locking mechanism (122) comprises a lever element (124) which is displaceable between an active position, wherein the lever element (124) interacts with the plunger (70) and the hollow sleeve (16) of the filling adapter (12) so as to prevent the plunger (70) from being moved from its filling position in a distal direction when the injection device (10) is connected to the filling adapter (12), and an inactive position, wherein the lever element (124) allows a movement of the plunger (70) from its filling position in a distal direction when the injection device (10) is not connected to the filling adapter (12).
 14. Injection solution transferring system according to claim 13, wherein the lever element (124) of the plunger locking mechanism (122) comprises at least one foot element (130) which is adapted to be contacted by the filling adapter (12) when the injection device (10) is connected to the filling adapter (12), in order to maintain the lever element (124) in its active position, and/or wherein the lever element (124) of the plunger locking mechanism (122) comprises a stop device (134) which is adapted to contact an abutment surface (136) of the plunger (70), when the lever element (124) is arranged in its active position, in order to prevent the plunger (70) from being moved from its filling position in a distal direction when the injection device (10) is connected to the filling adapter (12).
 15. Injection solution transferring system according to claim 14, wherein the plunger locking mechanism (124) further comprises a retention device (138) which is adapted to interact with the at least one foot element (130) of the lever element (124), in order to prevent the at least one foot element (130) from becoming disengaged from the filling adapter (12) when the lever element (124), by the interaction between the filling adapter (12) and the foot element (130), is maintained in its active position. 